The professional coffee makers currently used to prepare espresso coffee are the manual and super-automatic type and any type of coffee maker basically comprises a cupboard containing a water circulation circuit, supplied by mains water and attached at least to one heating boiler for the production of hot water and steam, wherein the water heating and steam temperatures are controlled by the thermostatic regulation at pre-set levels, said boiler being connected by means of circulation pumps and flow regulation valves, with a brewing unit, comprising a brewing chamber into which the ground coffee is first introduced, said unit communicating by means of an outlet pipe with an underlying collection container, so that the water heated in the boiler or in the exchanger to the pre-set and constant temperature is made to circulate by means of the circulation circuit and, passing through the dose of ground coffee, contained in the brewing chamber, obtains the espresso coffee, which is then supplied through the outlet pipe, reaching the underlying container.
The espresso coffee collected in the container may also be mixed with milk and possibly further heated with hot steam.
In these types of coffee maker, the coffee beans are ground beforehand in suitable grinders of the traditional type, which may be separated or incorporated into the coffee makers, so as to provide the ground coffee to introduce into the relative brewing unit of the coffee makers.
In particular, manual coffee makers are provided with at least one filter-holder element applicable in a removable way underneath the relative brewing unit of the machine and comprising a cup-shaped container provided with a filter and attached to an elongated support handle gripped by the operator, and the ground coffee is introduced manually into said cup-shaped container acting as the brewing chamber by the barman, in the desired quantity and before the brewing cycle, said ground coffee being pressed manually into the filtering cup before applying the filter-holder element underneath the brewing unit, and the brewing cycle is then started, wherein the heated water passes through the ground and pressed coffee and the filter meshes, thus obtaining the espresso coffee, which is supplied into the underlying container at optimum pressure for espresso.
Then, on completion of brewing, the filter-holder element is removed from the coffee maker and the used pod is ejected from the cup, by shaking or lightly striking the filter-holder element to detach the used pod, which is then discharged into special collection containers.
With these types of coffee makers it is therefore possible to obtain espresso coffee of high quality and flavour, grinding the coffee beans and pressing the ground coffee in the cup with suitable pressure and, if necessary, adjusting the pressure and the water temperature for the brewing step in an optimal manner based on experience, thus obtaining espresso coffee with highly satisfactory results.
The filter holder may be used immediately for a new brewing cycle, wherein a further dose of ground coffee is introduced into it for the preparation of another espresso coffee, and in this condition, as a result of heat conduction, the filter holder remains hot and allows a brewing cycle to be obtained in an optimal manner, with shorter heating time and therefore lower heating power.
These types of machines are particularly suitable for use in restaurants, bars and similar premises, since they prepare and supply high-quality espresso coffee at a high productivity rate, as a function of the requirements of individual users.
Unlike these manual coffee makers, the super-automatic coffee makers currently used are manufactured with several component parts realised and functioning in a slightly different manner, to allow continuous preparation of espresso coffee. In particular, in these super-automatic coffee makers, the grinder is always incorporated into the machines themselves and communicates with a vertical cylinder, housing a vertically sliding piston, controlled by an electric motor of the machine and movable from a lowered position to a raised position, and vice versa.
Said piston communicates with the hot water pipes fitted to the machine's boiler and act as presser and infuser, while the cylinder is provided with a collection cup of a dose of ground coffee. When the piston is moved into the high position, the collection cup is in the position communicating with the grinder outlet pipe and when the user selects a cup of coffee, the grinder is activated automatically and a dose of ground coffee is introduced into the collection cup. Subsequently, the piston is automatically and gradually lowered towards the cup containing the dose of ground coffee, so that, when the piston is in the completely lowered position, the dose of ground coffee is pressed against a corresponding striking block, with constant pressure which is independent of the quality of the espresso coffee to be obtained. Then, by means of the piston with the dose of coffee, the hot water is introduced through automatic opening of a solenoid valve inserted in the hot water pipes, with consequent passage of the hot water through the ground coffee and obtaining of a cup of espresso coffee, which is then supplied by means of a pipe to an underlying collection container. When brewing is completed, the hot water solenoid valve is automatically closed and the piston is once again moved into the high position, in which position an ejector cooperating with the cylinder cup is arranged, so that, in said position, said ejector acts against the used pod, ejecting it and discharging it into an associated collection container. The machine is thus prepared for a subsequent brewing cycle, which is performed with the same operating sequences.
In general, solutions exist in automatic machines wherein the movements of the piston and cylinder are inverted.
However, super-automatic espresso coffee makers thus realised do not allow an espresso coffee maker with the same quality features of manual machines to be obtained, both because the cylinder cup is the same for both single and double doses and because after ejection of each pod the cup is not cleaned precisely, with consequent mixing of the coffee residues of each cycle with the freshly ground coffee of a new dose, and obtaining of non-optimal brewing of this dose of coffee.